There exists a generally preferable need to launch projectiles at high velocity from launchers such as firearms. High velocity at the muzzle end of the barrel of a firearm means that whatever the weight and dimensions of the projectile, a sufficiently large gaseous expansion event has been provided behind the projectile to eject the projectile at the muzzle velocity measured.
In addition to the above well known need is the strategic and actual advantage of firing a multitude of projectiles at about the same time in the same direction. Use of a firearm having such characteristics can satisfy some of the many military needs associated with direct and indirect fire weapons and firearms usage in offensive and defensive environments.